Optimization of Thermoelectric Generators in the Presence of Heat Losses and Fluid Flows

This paper investigates the optimization of thermoelectric generators considering heat exchangers, heat losses, and fluid flows. This paper expands on the approach used in the literature for a constant temperature difference and constant heat flux in order to consider the presence of heat losses and fluid flow as a heat source and sink. Updated thermal impedance matching criteria are developed as an optimal ratio of a heat exchanger to module conductance. The constant figure of merit links the thermoelectric conductance to the internal resistance, and the optimal load resistance is provided for each condition. An effective thermal conductance is defined for the thermoelectric modules (TEMs) to consider the effect of electrical load resistance on the thermal transport and is validated by experimental data. It is demonstrated that maximizing the thermal conductance of the heat exchangers is the first step to achieve maximum power, regardless of the conductance of the TEM. Once the heat exchangers are fixed, updated thermal impedance matching criterion should be used to define the module's conductance. Optimal conditions under constant heat flux are shown to be completely different when considering heat losses.